Multiple use of wave shaping circuits for tone production



Dec. 7, 965 J. c. COOKERLY ETAL 3,222,447

MULTIPLE USE OF WAVE SHAPING CIRCUITS FOR TONE PRODUCTION Filed Nov. 20. 1961 WAVE SHAPE WAVE SHAPE WAVE SHAPE SIG. GEN.

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TTORzE Y5 United States Patent O 3,222,447 MULTIPLE USE OF WAVE SHAPING CIRCUITS FOR TONE PRODUCTION Jack C. Cookerly, 7655 Atoll Ave., North Hollywood,

Calif., and George R. Hall, 13613 Huston St., Sherman Oaks, Calif.

Filed Nov. 20, 1961, Ser. No. 153,581 3 Claims. (Cl. 84-119) This invention relates generally to tone generation systems and more particularly to a novel network employing wave shaping circuits for use with musical instruments having manuals for generating a large number of different tones such as organs, pianos, accordions, and the like.

Electrically operated instruments employing wave shaping circuits for providing different quality tones have been provided heretofore. In the case of an organ, for example, there may be as many as sixty-one manually operable keys for generating tone signals. Each tone signal generated upon manual operation of one of these keys may be passed through a wave shaping circuit which can include mono-stable and bi-stable oscillators, frequency doublers, frequency dividers, various integrating and differentiating systems, and so forth, to provide octave effects and many different qualities of tone. Ordinarily, a duplicate wave shaping circuit will be associated with each of the keyed signals so that in the case of a sixty-one key manual, sixty-one completely self-sufficient wave shaping circuits would be required. As a consequence, the instrument becomes bulky in size and relatively expensive to produce.

With the foregoing in mind, it is a primary object of this invention to provide a novel electrical network for instruments of the foregoing type in which the bulk and expense may be greatly reduced and yet in which the desired effects are still provided.

More particularly, it is an object to provide an improved tone production system for instruments in which the total number of wave shaping circuits heretofore deemed necessary is greatly reduced to the end that the instrument becomes smaller, less expensive, and more reliable than instruments heretofore capable of similar results.

Briefly, these and many other objects and advantages of this invention are attained by providing only that num ber of wave shaping circuits corresponding to a given number of tones which might be normally played simultaneously. In other words, by assuming that no one would ever use more than a given number of keys at one time, and by providing a similar number of wave shaping circuits, the various wave shaping circuits themselves may be shared among the total number of tone signals generated by the keys.

In accordance with the preferred embodiment of the invention, this sharing of the wave shaping circuits is accomplished by a switching means in which successive tone signals generated are automatically passed to only those wave shaping circuits which are not already connected to receive a tone signal. In this manner, the number of wave shaping circuits are optimized for any one particular instrument. For example, in an organ, one would normally play no more than eight tones simultaneously even if using both hands. There would thus be required only eight wave shaping circuits even though there may be 3,222,447 Patented Dec. 7, 1965 sixty-one keys on the manual. In the case of an accordion, five wave shaping circuits would generally be sufficient.

A better understanding of the invention will be had by referring to one embodiment thereof schematically illustrated in the accompanying drawing, in which:

The single figure illustrates one type of switching means for enabling only a few wave shaping circuits to share tone signals generated by a larger number of keys.

Referring to the left portion of the drawing, there are shown a total number of keys 1, 2, 3, 4, 5, 6, and so forth. These keys may correspond to organ, piano, or accordion keys on a manual and may normally be played with one or both hands, various chords being formed by playing a given number of keys simultaneously. In the lower portion of the drawing, there are shown a plurality of wave shaping circuits 11, 12, 13, and so forth, which correspond in number to the given number of keys which might normally be played simultaneously. The outputs from the respective wave shaping circuits pass to a reproducing means including a conventional amplifier 14 and loud speaker 15. The given number of wave shaping circuits is considerably less than the total number of keys.

Connected between the various keys and wave shaping circuits is a switching means capable of selectively passing tone signals generated upon operation of the keys to the wave shaping circuits in such a manner that any one wave shaping circuit will pass successive tone signals only if it is not already connected to receive a tone signal by the switching means.

Thus, the various inputs to the wave shaping circuits are shown at 16, 17, and 18. These inputs are respectively connected to a plurality of series circuits including series connected switches 16a, 16b, 16c, 16d, 16e, 16 and so forth, constituting a first one of the series circuits; 17a, 17b, 17c, 17d, 17e, 17 and so forth, constituting a second one of the series circuits; 18a, 18b, 18c, 18d, 18e, 18 and so forth, constituting a third one of the series circuits, and so on, there being provided a number of series circuits equal to the given number of wave shaping circuits.

Associated with the series circuits respectively are a plurality of groups of circuits, each of the groups including a number of individual switches. For example, the first group of individual switches are designated 1a, 2a, 3a, 4a, 5a, 6a, and so forth; the second group of individual switches are designated 1b, 2b, 3b, 4b, 5b, 6b, and so forth; the third group, 1c, 2c, 30, 4c, 50, 6c, and so forth. As shown, the first group of individual switches 1a-6a are connected to receive tone signals from the corresponding keys 1-6.

As an example, the key 6 is connected to a signal generator 19 which will be triggered upon operation of the key to provide a tone signal to the individual switch 6a.

The switch 6a is schematically illustrated as a relay switch having an associated relay coil 20 which will be energized by the tone signal to throw the switch 6a to a terminal connecting to a point in the first series circuit. The one series switch 16 preceding this point of connection into the series circuit is ganged to the individual switch 6a as indicated by the dashed lines so that the switch 16 is also thrown to connect to an individual switch 6b in the second group. If another tone signal is passed through the switch arm 16 when in its operated position,

this second tone signal will energize a relay coil 21 to operate the individual switch 6b and cause it in turn to connect to a point in the second series circuit. This switch is similarly ganged to the series switch 17 f preceding such point in the second series circuit to cause it to connect to another independent switch 6c in the third group. This latter switch is arranged to be operated by a relay coil 22 upon receiving a tone signal, and so forth.

The various portions of the switching means associated with the other keys are identical in operation to the key 6 described above. It will be noted, however, that the actual number of series switches in the successive series circuits are successively decreased by one, and the total number of individual switches in each of the groups are always one greater than the number in the series circuits with which they are associated through the ganged means indicated by the dashed lines.

In the operation of the illustrated tone producing system, the switches are normally in their solid line positions when no tone signals are generated. Assume first that key number 1 is operated. The tone signal from the corresponding signal generator will then pass through the associated relay coil operating the switch 1a to connect to the input line 16 of wave shaping circuit 1.1. The output from the wave shaping circuit will then pass through the amplifier 14 and loud speaker 15 to provide a desired tone. While this tone is being played, assume that the operator operates key number 2. In this instacne, the switch 2a will be thrown, which action would normally connect the generated tone signal to the input of the wave shaping circuit 11. However, upon operation of the switch 1a the switch 16a was simultaneously operated through its ganged connection so that the signal from the switch 2a will pass through the switch 16a to the individual switch 1b. The associated coil with switch 1b will then be energized to throw the switch 1b to the input line 17 connecting to the wave shaping circuit 12. The tone generated by the key 2 will then pass through the wave shaping circuit 12, this tone signal being blocked from the wave shaping circuit 11 which is already in operation.

In a similar manner, assume for example that key is operated while keys 1 and 2 are still depressed. In this case, the switch 5a will be thrown, and the tone signal from key 5 will pass through the series connected switches 16d and 16c to the switch 16b. However, since switch 16b is already thrown because of the operation of key 2, this signal will then pass to the individual switch 21) which will be caused to operate by its associated relay coil to connect to the switch 17a. The switch 17a is also thrown because of its ganging to the switch 1b which has been operated by the signal from key 2. Therefore, the signal will pass to the individual switch 10, causing it to operate and connect to the input 18 of the wave shaping circuit 13. Thus, the tone signal generated by operation of key 5 will be passed to the wave shaping circuit 13. If new another key is operated such as the key 6, a similar process will follow to the next successive wave shaping circuit.

Before the number of keys depressed simultaneously exceed the number of Wave shaping circuits, however, one or more of the original keys will be opened since it is assumed that no more than a given number of keys are ever played simultaneously. For example, assume prior to the operation of key 5 that the player releases key number 2. In this case, the switches 2a and 16b will return to their normal solid line positions so that the signal from key 5 will pass through switches 16a, 15c, 16b and 16a which latter switch is still thrown because of the continued operation of key 1. The signal then passes through individual switch 1b to the input of the wave shaping circuit 12 which was formerly used for the tone signal from the key 2 but may now be used for the signal from key 5.

It will be understood, of course, that the actual number of wave shaping circuits required will depend upon the type of instrument and the given number of keys ordinarily selected for playing simultaneously. In most instances, however, this given number of wave shaping circuits need not exceed eight, even though there may be sixty-one or more individual keys to be played.

From the foregoing description, it will thus be evident that the present invention has provided a greatly improved tone production system in which multiple use of wave shaping circuits is employed.

While a simple electrically operated relay type mechanieal switching has been illustrated for ease in explanation, it should be understood that many equivalent means for opening and closing circuits could be employed such as solid state devices, vacuum tubes, and so forth. The switching means itself is therefore not to be thought of as limited to relay type switching, and the term switching means as well as the term switch is meant to apply to simple mechanical type switches as well as equivalent switching as may result, for example, from the use of diodes, transistors, and vacuum tubes.

What is claimed is:

1. In an instrument including a total number of tone signal generators and a like number of operating keys therefor in which no more than a given number of said keys less than said total number are normally played simultaneously and which includes a reproducing means providing sounds initiated by said tone signals, the combination including:

(a) a plurality of wave shaping circuits having outputs connected to said reproducing means and equal in number to said given number; and

(b) a switching means connected between said total number of keys and the inputs to said wave shaping circuits, said switching means connecting successive tone signals played to only those wave shaping circuits which are not already connected to receive tone signals whereby any combination of notes played simultaneously not exceeding in number said given number are individually passed to said wave shaping circuits so that said given number of wave shaping circuits are sufiicient to accommodate tone signals selected for normal playing from said total number of keys.

2. An instrument according to claim 1, in which said switching means includes:

(a) a plurality of series circuits respectively connected to said plurality of wave shaping circuits, each of said series circuits including a number of switches connected in series with each other when in closed positions;

(b) a plurality of groups of circuits respectively associated with said plurality of series circuits, each of said groups of circuits including a number of individual switches, a first group having its individual switches connected to receive said tone signals respectively in response to operations of said keys and in which a tone signal received on any one of said individual switches connects said one individual switch to a first of said series circuits at a given point to pass said tone signal to a first of said wave shaping circuits, the one series switch in said first of said series circuits preceding said given point being ganged to the said one individual switch carrying said tone signal to open and connect to an individual switch in a second group, said individual switch in said second group upon receiving a tone signal, connecting said tone signal to a second of said series circuits at a point to pass said second mentioned tone signal to a second of said wave shaping circuits, the series switch in said second of said series circuit preceding said second mentioned point being ganged to the individual switch carrying said second mentioned tone signal to open and connect to an individual switch in a third group, and s0 forth whereby tone ARTHUR GAUSS, Primary Examiner.

10 J. S. OVERHOLSER, Examiner.

References Cited by the Examiner UNITED STATES PATENTS Larson.

Haller 8'1-1.19 X Hilborn 84--1.19 X Brand et al. 841.11 

1. IN AN INSTRUMENT INCLUDING A TOTAL NUMBER OF TONE SIGNAL GENERATORS AND A LIKE NUMBER OF OPERATING KEYS THEREFOR IN WHICH NO MORE THAN A GIVEN NUMBER OF SAID KEYS LESS THAN SAID TOTAL NUMBER ARE NORMALLY PLAYED SIMULTANEOUSLY AND WHICH INCLUDES A REPRODUCING MEANS PROVIDING SOUNDS INITIATED BY SAID TONE SIGNALS, THE COMBINATION INCLUDING: (A) A PLURALITY OF WAVE SHAPING CIRCUITS HAVING OUTPUTS CONNECTED TO SAID REPRODUCING MEANS AND EQUAL IN NUMBER TO SAID GIVEN NUMBER; AND (B) A SWITCHING MEANS CONNECTED BETWEEN SAID TOTAL NUMBER OF KEYS AND THE INPUTS TO SAID WAVE SHAPING CIRCUITS, SAID SWITCHING MEANS CONNECTING SUCCESSIVE TONE SIGNALS PLAYED TO ONLY THOSE WAVE SHAPING CIRCUITS WHICH ARE NOT ALREADY CONNECTED TO RECEIVE TONE SIGNALS WHEREBY ANY COMBINATION OF NOTES PLAYED SIMULTANEOUSLY NOT EXCEEDING IN NUMBER SAID GIVEN NUMBER ARE INDIVIDUALLY PASSED TO SAID WAVE SHAPING CIRCUITS SO THAT SAID GIVEN NUMBER OF WAVE SHAPING CIRCUITS ARE SUFFICIENT TO ACCOMMODATE TONE SIGNALS SELECTED FOR NORMAL PLAYING FROM SAID TOTAL NUMBER OF KEYS. 